Mixxx is free, open-source DJ software for Windows, macOS and Linux. It mixes digital music through four playback decks, with controls for aligning beats, moving between tracks and changing the sound during a live set. A mouse and keyboard can operate the decks, while MIDI/HID controllers and timecode vinyl provide other ways to perform.
The Mixxx library and track preparation
Mixxx keeps a searchable library of your music and analyzes tracks for tempo and musical key. Sorting by these values helps identify songs with compatible rhythms or harmonies. Playlists hold tracks in a chosen order; crates group them without a fixed sequence or duplicate entries.
The library reads track tags, lets you edit their contents and can look up missing information through MusicBrainz. Its preview deck plays a candidate through headphones without occupying a main deck. Mixxx also reads external libraries from applications including Traktor and Serato, and exported Rekordbox libraries on removable devices. These views provide access to existing music and playlists; individual library formats determine which additional cue or loop information transfers.
Supported audio includes MP3, FLAC, WAV, AIFF, Ogg Vorbis and Opus. AAC playback depends on the platform and build, with Linux support disabled by default. DRM-protected files and ALAC audio are unsupported.
Deck mixing
Each deck has a scrolling waveform for the current passage and an overview of the whole song. Beat markers help compare timing, while cues and loop markers show prepared positions. The overview can jump to another part of the track; the larger waveform also supports mouse scratching and temporary speed adjustments.
Beatmatching involves matching both tempo and the position of the beats. Mixxx provides rate sliders and temporary pitch bends for doing this manually, or Sync for matching tracks automatically. Automatic alignment depends on a correct BPM value and beatgrid. Grid controls let you shift, stretch or compress the markers when analysis places them incorrectly.
Sync Lock keeps participating decks linked as their tempo changes. Keylock preserves musical pitch when playback speed changes, while separate pitch controls transpose a track without changing its tempo. This allows tempo matching and harmonic adjustment to be handled independently.
The mixer combines the decks through channel faders, equalizers and a crossfader with an adjustable curve. Headphone cueing lets you hear an incoming track independently of the audience mix when a headphone output is configured. ReplayGain uses existing loudness tags or analyzes tracks to adjust their loading level, reducing abrupt differences between recordings.
Cue points
Hotcues mark passages that you can trigger directly instead of seeking through the song. Beat loops repeat a selected number of beats, and saved loops can occupy hotcue slots for later recall. Quantization places cue and loop actions on the beatgrid, tying their timing to the track’s analysis.
Slip mode changes what happens after a temporary intervention. While you scratch, reverse or loop the audible track, its normal playback position continues silently. Leaving the intervention returns the sound to the point the song would have reached, rather than leaving the performance behind by the duration of the effect.
Sampler decks
Mixxx has up to 64 sampler decks for layering short sounds, jingles or additional tracks over the main decks. These miniature decks include cue triggering, gain, playback-rate and synchronization controls. A sample can therefore be retriggered from its cue or brought into time with a playing deck, with its level controlled separately.
Effect chains
Four effect units process audio from decks, microphones, auxiliary inputs or the main mix. Each unit holds up to three effects in series, so changing their order changes the signal that reaches the next processor. Routing one channel through several units extends the chain beyond a single unit.
Mixxx exposes individual effect parameters and a metaknob that moves linked parameters together. You choose which controls follow that knob and how their movement relates to it. A dry/wet control balances the original and processed signals, while effect previewing in headphones lets you hear the processing before bringing it into the main mix. Effects follow the faders, allowing an echo or reverb tail to continue after its source is faded out.
Controller mappings and timecode vinyl
Built-in mappings connect supported DJ controllers to Mixxx’s deck, mixer and effect controls. Custom mappings associate MIDI or HID messages with software functions; JavaScript scripting handles more complex behavior than a direct button assignment. The available mapping determines how a particular device’s knobs, pads and indicators operate.
Timecode control uses a different input. An audio interface receives the signal from a supported control record or CD, and Mixxx interprets it to move the loaded digital track. Absolute mode follows position as well as speed, allowing needle-drop seeking; relative mode follows movement without seeking to the needle’s absolute position. Timecode needs suitable stereo inputs, and compatibility depends on the control medium. Vinyl passthrough also allows ordinary records to enter the set.
Auto DJ
Auto DJ loads tracks from a queue and performs crossfades automatically. The queue can contain manually selected music or draw from assigned crates. Transition modes can use marked intro and outro sections, play the full files or skip their leading and trailing silence. For timed crossfades, you choose the transition duration.
Auto DJ controls playback and the crossfader without judging the tracks’ rhythms, frequency content or relative loudness.
Live inputs
Four microphone inputs and four auxiliary inputs bring live sources into Mixxx alongside the decks. The microphone Talk control adds speech to the main output, and input gain controls set its level. These sources can participate in the effects routing as well as the mix itself.
Set recording
Recording saves the main output as an audio file, or captures a configured input from an external mixer. Mixxx supports WAV, FLAC and Ogg Vorbis recording, with MP3 available through the separate LAME library. Recording controls include metadata, file splitting and CUE files, and saved sessions appear in the library’s Recordings view.
Radio streaming
For live distribution, Mixxx sends an audio stream to an Icecast or Shoutcast server, which delivers it to listeners. Icecast accepts MP3 or Ogg Vorbis streams; Shoutcast uses MP3. Stream metadata can show the playing track’s artist and title or use custom text for the programme.
